Keeping diode lasers cool is a major concern for most diode laser applications. For high power diode laser arrays, thermal management is a critical concern. Modern diode laser array designs can generate a heat flux greater than 400 W/cm2. The traditional way for packaging an edge emitting diode array is by stacking the diode lasers vertically with cooling and electrical connection plates sandwiched in between. The diode active area, which generates tremendous amount of waste heat, is a considerable distance from the coolant in the traditional design. Also, several layers of solder and an electrical insulation layer must be used resulting in additional thermal resistance. This design results in a longer cooling path than is desirable in order to maintain uniform cooling for all diodes. The longer cooling path results in higher diode temperature, lower efficiency, shorter diode life, slower thermal response and non-optimum temperature control. In addition, it is difficult to replace malfunctioning bars in this type of stack.
High divergence and astigmatism are two additional problems associated with diode laser output beams. Microlens arrays are often utilized for correcting the divergence. There are several ways to collimate the beam. For example, two sets of cylindrical lens arrays, planar micro lens arrays, and diffractive optics are often used. However, complexity, aberration and/or diffraction efficiency are concerns that arise from using these types of features.